Radio receiving apparatus



E. A. WIDMANN ET AL RADIO RECEIVING APPARATUS vJuly 3 1, 1928.

Original Filed June 20. 1922. 2 Sheets-Sheet 1 July 31, 1928. 1,679,194

E. A. WIDMANN Er AL RADIO RECEIVING APPARATUS Original Filed June 20. 1922 2 Sheets-Sheet 2 @Uf-l Patented July 31, 1928.

UNITED STATESPATENT OFFICE.

EUGENE A. WIDMANN, OF BROOKLYN, NEW YORK, .AND FRANK D. LEWIS, 0F WEST ORANGE, NEW JERSEY, ASSIGNORS, BY MESNE ASSIGNMENTS, TO PATHE PHONO- GRAPH & RADIO CORPORATION, A CORPORATION 0F NEW YORK.

RADIO RECEIVING APPARATUS.

Application filed June 20, 1922, Serial No. 569,692. Renewed July 7, 1927.

This invention relates to radio receiving apparatus, and more particularly to the'socalled loud speakers or equivalent devices which are usually comprised in such apparatus for reproducing the sound vibrations communicated to the armature of tbe receiver at large volume by the energization of the electro-magnets thereof in accordance with receiving signals.

The invention aims primarily to provide means for avoiding the objectionable chattering or blasting which frequently arises during receiving as a result of contact between the armature and the pole pieces of the magnets disposed within the case of the telephone receiver; such means preferably comprising an adjusting screw which passes through the case and is connected to control the normal position of the armature with relation to the ends of the pole pieces, so that it will be constantly spaced from, andl prevented from striking against, the pole pieces at all times.

The invention also contemplates the employment, as the amplifier proper, of a large,

conical diaphragm or vibratile material,` substantially identical with the amplifier or diaphragm now in use in the type of talking machine known commercially as the Actuelle, This diaphragm takes the place of the sound-box and horn of the more conventional talking machine, and it has connected to its apex one end of a transmission element, the other end of which is connected to a stylus holder; the arrangement being such that the vibrations imparted to the stylus holder consequent upon the travel of the stylus along the sound grooves in the record are transmitted through the aforesaid ele ment to the big diaphragm, which is thereby caused to vibrate piston-fashion, with the result that the original sound waves are regenerated in their initial tonal strength`and quality in free, unconfned atmosphericair The diaphragm of the present invention acts in precisely the same manner and attains the same brilliant effects, so that it is peculiarly suited for use in receiving and reproducing musical radio broadcasting.

In the same general connection, the invention further contemplates the employment of the vibrating armature or diaphragm of the telephone receiver as a means for effecting the vibration of the transmission element and the conical amplifying diaphragm; as well as the provision of an improved rocking or vibrating support or carrier located between the armature and the transmission element and to which the former is attached, so that it acts in a manner similar to the stylus lever of a talking machine and may, in fact, be so regarded.

The invention also contemplates other and further improvements and features of advantage which will be explained as the description proceeds';.but itis to be understood that no limitation to the precise details involved in the present disclosure is intended, since the invention is obviously susceptible of modilications and changes within its scope as subsequently claimed. It is also apparent that parts of the invention may be used to the exclusion of others, and in other and different environments.

Heretofore in the art, loud speakers have generally included a pair of windings, one comprising the armature energized from the output circuit of the last stage of electron tube amplilication in the radio receiving apparatus, and the other forming a field Winding energized from a low voltage storage battery. The requirement of the storage battery excitation has always been a disadvantage from the viewpoint. of rapidly dis' charging the electron tube filament lighting battery usually employedfor thisl purpose or demanding the additional expense of another storage battery. Other forms of loud speakers heretofore employed have included the ordinary telephone receiver acoustically connected with a horn.l The volume of sound reproduction of such devices has been limited 4and has evolved the inherent 'disadvantages of unclear and confused reprfliduction under conditions of strong signa s.

In the accompanying drawings, showing one embodiment of the present invention:

yFigure l is a vertical sectional view of the complete invention, only a portion of the diaphragm appearing.

Fig. 2 is a plan view of the telephone receiver with the cover removed.

Fig. 3 is a fragmental side elevation of the receiver with the cover in place.

Fig. 4 is a part sectional'side elevation showing the transmission element disposed at right angles to, instead of parallel with, the armature.

Fig. 5 is an enlarged detail section showing the fiexible connection between the vibration transmission connection and the stylus lever or interponent carrying the armature.

Referring more particularly to the drawings, 7 indicates a large conical or equivalent diaphragm of paper or other suit-able vibratile material, of the type now utilized in the commercial Actuelle; and 8 the vibration transmission element, which is connected at one end to the apex of the cone and which is likewise similar to, though much shorter than, the corresponding part or element in the above-mentioned machine. The transmission element 8 preferably takes the form of a thin wall-ed, tubular metal rod which, in the construction illustrated in Fig. 1, is disposed horizontally.

The radio-receiving equipment may, in the main, be of conventional character and may involve the usual circuits which may be tuned to resonance with the .incoming signals and electron tube amplifiers for increasing the amplitude of the received signals; illustration thereof being omitted as not concerned in the actual invention. An output circuit of the last stage of electron tube amplification is included, as usual, and in this circuit the loud speaker telephone receiver is connected. The receiver, as here shown, comprises a cup-shaped case 9, provided with a cover 10 and containing twoelectromagnet coils 11, having upright pole pieces 12 which extend through them. rlhese pole pieces preferably take the form of fiat strips having laterally off-set lower ends which extend obliquely therefrom and beneath the ends of a horse-shoe bar or permanent magnet 14 to which they are fastened; the arrangement being such that the bar 14 is supported slightly above the'bottom wall of the case. Current is supplied to the magnet coils in some suitable manner; for instance, by means of plug connections (not shown) to which the circuit wires are fastened, the plugs being removably fitted in sockets 13 in the case, indicated in dotted lines in Fig. 2. The coils are connected by short conductors 15 to spring contacts 16 mounted on binding screws 17 which engage therplug contacts. The two contact strips 16 rest upon the top of a projection or boss 18 disposed within and forming an integral part of the case 9, and are held in place by nuts 19 carried by the binding screws; the sockets 13 extending into this boss, whereby the plugs or tips may be electrically connected in circuit under the binding screws.

The upper ends of the pole pieces 12 project a short distance above the tops of the coils 11, and immediately above said ends there is arranged the armature or diaphragm 2O of the telephone receiver. This element preferably consists of a rectangular plate, which, as previously stated, is carried by an element that corresponds broadly to the stylus lever of a talking machine soundbox. In the construction illustrated, the carrier lever comprises a main horizontal arm 22 which extends inwardly of the case from ahorizontal cross-piece or fulcrum bar 23. This bar 23 is supported by a pair of leaf springs 24 which are themselves carried by projecting screws 25 attached to a plate 26 that is secured in a cavity or recess 27 formed in the inner surface of the vertical wall of the case; displacement of the screws being prevented by nuts 28..,carried thereby. The two springs 24 extend in opposite directions, as shown, and they are attached at their outer ends to the screws, while their inner ends are bent or coiled around the rounded ends of the cross-bar 23. The aforesaid ends are recessed for engagement by a pair of knife pivots 29 which project outwardly from plate 26, thereby enabling a rocking movement of the lever in either direction about the horizontal axis of bar 23; the springs 24, however, tending to normally maintain said lever in neutral position.

The horizontal arm 22 of the stylus lever or carrier extends over the armature 20 at its free end, and is preferably cut away at its lower surface to provide a seat 30, in which the armature fits; the two parts being fastened together by a screw 3l. Arm 22 is disposed in line with the center line of v the armature; and since said arm is arranged symmetrically with relation to the fulcrum bar 23 which, in turn, is balanced by the knife pivots 29, the armature will likewise be nicely balanced, and it and the supporting lever will rock or vibrate as a unit consequent upon the current impulses in the output circuit through the magnets during the receiving operation. To transmit these vibrations to the amplifying diaphragm 7, the connecting tube or rod 8 has its inner end attached to the carrier lever; and in one form of the invention, said lever is provided with a second arm 32 (Fig. 1), which extends upwardly from the point where the horizontal arm 22 and the fulcrum bar 23 intersect. The vertical arm 32 is formed at its upper end with a transverse opening 33 (Fig. 5), which is wider at its ends than at its center, thus providing two rounded portions or seats for the reception of the convex faces of a pair of plano-convex nuts 34 mounted on the end of rod 8 at opposite sides of said arm. In this way, a ilexible connectionV between the leverarm and the transmission rod is obtained which enables the movements of the former to be transmitted to the latter without occasioning distortion.

For the purpose of preventing chattering or blasting during receiving, due to the armature 20 striking against the tops of the pole pieces 12, we provide an adjustable means or device for constant-ly maintaining the armature spaced from the pole pieces, or in other words, for avoiding impact of the former upon the latter. This device may advantageously comprise a finely-threaded screw 35 which projects upwardly through a threaded opening formed in the bottom of the case and continued through the boss 18; the free upper end of the screw extending above the top face of the boss and having attached to it a light spring 36 which projects over and is fastened to the armature. A small screw 37 is set into .the end of the adjusting screw 35 and-passes through a hole in the spring to secure the two together, and one or more fiber washers 38 may be interposed between the spring and the end of the adjusting screw in order to prevent vibration. The lower portion of the adjusting screw projects below the bottom `of the case and terminates in a knurled operating head 39; and a nut 40 is fitted on said portion and is adapted to be tightened against the under side of the case bottom to hold the screw in adjusted position.

It will be apparent, therefore, that by turning the adjusting screw in the proper direction, it may be caused to move upward, and that in so doing it will raise the armature owing to the provision of the connecting spring 36. This will have the obvious ell'ect of spacing the armature from the pole pieces, the movement of the armature being transmitted to the arm 22 of the carrier or stylus lever which is thereby caused to rock' slightly about the axis of its fulcrum bar 23. In practice, it will be sufficient to space the armature and the pole pieces about .001 apart.

In the construction above described and illustrated in Fig. 1, the transmission element 8 isvdisposed horizontally and in par-l tical arm 32, which latter will then be unnecessary and may be omitted. 'This vertical arrange-ment is represented in Fig. 4.

Any suitable means or devices may be provided for supporting the-receiver and t-he large amplifying diaphragm in either of the two arrangements above described; and both of those parts may be disposed in any desired relation to the various instrumentalities' com rised in the radio-receivingapparatus.

e claim as our invention:

1. A loud speaker for radio-'receiving sets, comprising a telephonereceiver embodying a case, an electro-ma net` therein, an armature cooperative wit the magnet, and a 80 spring-balanced carrier tolwhich the armature is attached fulcrumed within the case on the side wall thereof; a vibratory ampli-- lier disposed wholly external to said case; and a vibration transmission connection leading from said carrier to said amplifier to vibrate the latter in .accordance with the movements of the armature.

2. A loud speaker for radio-receiving sets, comprising a small 'telephone 'receiver em- 90 bodying a case, an electro-magnet therein, an armature cooperative with the magnet, and a balanced carrier for the armature pivot' ally mounted within the case;v a large, vibraltory amplifying diaphragm disposed wholly external to said case; a vibration-transmission rod connected with the armature carrier and leading from the samedirectly to the vcenter of said diaphragm; and an ad- 'i justing screw mounted in the case and con- 10U nected'to-move the armature toward or fromv the pole-piece or pieces of the magnet to regulate lts normal position with respect thereto.

3. A loud speaker for radio-receiving sets, comprising a watch-case telephone receiver embodying a cup, a cover therefor, and an electro-magnet an'd an armature for the same disposed within the cup; a large conical amplifying diaphragm disposed external to the telephone receiver; a vibration-transmission element connected at one end with the armature and leading through the cup directly to the apex of the conical diaphragm to vibrate the latter in accordance with the, movements of the armature; and an adjusting screw eX- tending through thecupl and connected to move the armature toward or from the polepiece or pieces of the magnet to regulate its normal position with respect thereto, said la( screw having a manipulating portion external to the cup.

4. A loud speaker for radio-receiving sets, comprising a watch-'case receiver embodying a cup, a cover therefor, and an electro-mag- 125.

net, an armature for the magnet and a balanced carrier for the armature all disposed within the cup; a large amplifying diaphragm disposed external to the telephoneV receiver; a vibration-transmission rod conlau nected at one end with the armature carrier position with respect thereto, said screw havand leading through the cup directly to the ing a manipulating portion external to the l center of the diaphragm to vibrate the latter cup. in accorda-nce with the movements of the ar- In testimony whereof, we have aixed our 5 mature; and an adjusting screw extending signatures.

through the cup and connected to move the armature toward or from the pole-piece or 'EUGENE A. WIDMANN. l pieces of the magnet to' regulate its normal FRANK D. LEWIS. 

